The 75 Gr. Steel BH Adaptors

[Dr. Ed Ashby]

Ben,

We didn't get them on every shot either - but we did get them on about 10% of the heavy bone hits (I'd have to check to get the exact percentage). Like so many weak-points, they show up more on angular impacts. To me, one failure that I could have prevented is something that haunts me; it's one too many.

Ed
TGMM Family of the bow

[SlowBowinMO]

It's the "snap off" tendency you're seeing that concerns me, that would essentially render the arrow immediately useless for the mission it started on.  I'd rather see them bend a little than break off like that.

I see some torture testing of my own in the very near future!    

[LKH]

I wonder if it is endemic to all the 75's or did you just get a bad batch?  Maybe someone who has had good luck could break one off at the junction and see if the thin metal issue is longterm or just one batch?

[BobW]

Doc:

I did some "highly scientific" research in the 75g steel adapters I have (from 3-R or KK - don't remember which).  Based on placing a wire into the bored out section, and then aligning it to the outside, the depth of the bore is to the last "grip ring" - 12mm.  This leaves approx 2mm of solid base.  My heads also do not have the reverse chamfer at the base where it would mate to the shaft.  Sorry, no pictures.

Could there be a "brand" problem?

Curious to others findings.

BobW

[BobW]

Further review of your photograqphs reveals that my adapter shafts also have a step down to the threaded section, and fewer "grip rings".  Wall section is also 2mm thick.  Appears to be a different product.

BobW

[SlowBowinMO]

Interesting stuff.

LKH, that is exactly what I intend to do.

BobW, as far as I know all the steel adapters have been made by PDP but they certainly may have changed them a bit over the years.

Mike Walker, good point on the minor change at that spot.  I hadn't noticed it until you pointed it out.

[BobW]

The ones I have look like this (sorry for the poor photography)
 

[Dr. Ed Ashby]

I'm hoping that this is just a 'brand' problem. These particular tapers came from 3 Rivers, about 3 months ago. All of them have the same depth cavity inside the taper, and all have the correct 75 grain weight. If you're using 75 grain steel adaptors, it appears that it would be a very good idea to check them out.

Just playing around a few minutes ago, I mounted a 190 gr. field point on a new out-of-the-pack taper and screwed it into a shaft having a 100 grain brass insert. Holding about half-way up the shaft, a moderately sharp srtike against the metal workbench, at about a 30 degree angle, snapped the taper; just like all those that have broken in testing. I'll guarantee that strike was far less than it would have been from even a fairly light-draw bow.

Ed
TGMM Family of the Bow

[cch]

I have some 75gr steel adapters from 3 Rivers that I bought in 06 and they are long tapered ones just a hair shorter than the 100gr ones. I stuck a screw down the hole and it came up quite short maybe a 1/16" from the bottom of the taper. I then did the same thing with the 100gr ones and the hole is drilled much deeper in them. My 75gr ones have deeper rings that go to a straight shaft. I wish I knew how to post a picture. I think they changed the design for cost reasons.

[Dr. Ed Ashby]

When I get back, I think I'll be checking ALL the new BH tapers I just resupplied with against the one's I've been using (my last 'resupply' was about 2 years ago). I hope there hasn't been some 'improvement' (design or materials) that merely improved the manufacturer's bottom line!

Ed
TGMM Family of the Bow

[BobW]

my adapters are from last summer and from KK.  Seem to be good stuff.

[cch]

That will be interesting. I think all of the 75gr are short tapers now. Back when the only steel adapter was a 125gr I tried to drill out the inside and they broke just like yours did. I am going to keep the 75gr that I have for as long as I can. Thanks for the info Ed.

[BobW]

Ed,

On a parallel topic, is there a performance issue with the "short" steel tapers?

[SlowBowinMO]

I had a little time to experiment with this tonight.  In was not able to break the adapter, the adapter held but enough force was applied that the broadhead ferrule split!  I am scratching my head trying to figure out why you're having such poor results Dr. Ed, others have had no trouble and I get something like this.     There does not seem to be consistency.  Visually I would say this adapter is a match to yours Ed, it appeared to me to be same manufacture.  Here's a pic of what I got:

 


Hardly scientific I know but it's got me scratching my head.     I did check the depth of the hollowing out and it also seemed very shallow.  I checked a 100 in comparison and I'd estimate the 100 had 4 times the steel down at the base, compared to the 75.

[Jason Jelinek]

Could it be that the Grizzly's have a thicker ferrule of steel compared to the one your using and the 75 gr adaptor is the weak link.

[Russ Clagett]

What I may do is take the 100 grain adapters and apply them to the grinder until they're 75 grains, might take a few minutes but it they dont break....who cares?

I'll just take some off the tip...

[SlowBowinMO]

Jason, I don't know on that, the ferrule walls on the 190 Grizzly would certainly be thicker than the head above though so that could be a possibility.

Russ, that's a great idea.     Let us know how it turns out.

[Dr. Ed Ashby]

Tim,

Now you have me wondering if this batch is just faulty, but the thin metal holding the shank to the taper also just looks far too thin to hold up well (shown in the first photo). I've not had any of the broadheads damaged on the shots where the adaptor gave way; yes, all 190 Grizzly.

Here are all the numbers off the packages I have (if need be, I can take a photo of the pachet and post it). First numbers; C-01-B-23, then under the bar code is 4226-2. Can you match that up to the adaptors you have?

I retried the sharp-rap test on the workbench ... and there goes another adaptor. I tried to see if I could snap one off with just hand pressure, but it held up to that.

This is perplexing and troubling. If it's a temporing or fabrication problem, where was quality control? Each of theses 75 gr. adaptors I have seems to have this problem.

This has open my eyes to something I was beginning to take for granted. I've always used 125 gr. adaptors; they are all I'll use on my hunting arrows; and with no problem, but I think I'm going to start destruction testing a couple of saples from each lot of adaptors I buy, regardless of the weight - in essence, doing my own double-check quality control. The less left to chance, the better.

Let me know if you can match these numbers up to a manufacturing lot, or something of that nature. They may just be for stock control.

Ed
TGMM Family of the Bow

[SlowBowinMO]

Dr.Ed, thanks for the lot number information.  I will check mine against those for sure but will not be able to do so until later today.  If it is a batch problem maybe that accounts for the inconsistent results?  I believe only the manufacture probably knows what all the numbers mean, but I certainly should be able to tell if my lot matches yours or not.  I do know that my rough measurements of the depth of the 100 vs. the 75 would suggest finding a way to accommodate the extra 25 grains at least would be worth the trouble.  About 4 times thicker at the breaking point than the 75 from what I can tell.  Russ' idea of grinding down the 100 may be the ticket if a shorter or lighter adapter is needed, although so far the one's I've got seem okay.

[Java Man]

My guess would be the 4226-2, means they were made the 226th day of 2004, 2nd shift.  Its a typical manufacturing "Julian Date".  Makes tracing the product much easier.  That is, assuming I'm right.